Is Arthur's first meeting with Murray an imagination?

Question

In this movie, Joker, Arthur is in the audience during a live show hosted by Murray and Arthur is eventually invited onto the stage by Murray; Murray ends up hugging Arthur and call Arthur his son.

There are several things out of place in this scene:

• Murray shows compassion towards Arthur and goes far enough to embrace Arthur as his own son; later on in the movie, Murray is shown constantly mocking Arthur as a failed stand up comedian
• During their subsequent meeting, neither Murray or Arthur seem to recall their passionate first meeting and hugging.

Given Arthur's unstable character, is it possible their first meeting only happens in his own head?

Answer 1

Without doubt the first meeting happens entirely in Arthur's head.

• There is no reference to this meeting when Arthur's clip from his standup routine is exploited on Murray's show. I consider this an explicit, in-universe answer with no ambiguity.
• You've already referenced the second meeting. Murray should have said something in the green room had they met before.
• Immediately before the 'first meeting', we see Arthur transfixed with the television set as shown by his glazed eyes and the slow zoom towards the television itself. This is Arthur entering his imaginary state.